课程名称︰普通物理学甲上 课程性质︰必修 课程教师︰赵治宇 开课学院：工学院 开课系所︰化工系 考试日期（年月日）︰2010/11/18 考试时限（分钟）：10:20~13:10 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : 1. Describe the principle of Time-of-Flight Mass Spectroscopy.(8%) 2. Describe the principle of scan tunneling microscope.(8%) 3. A rocket whose initial mass is 850 kg consumes fuel at the rate R=2.3 kg/s. The speed u of the exhaust gases relative to the rocket engine is 2800 m/s. (a)What thrust does the rocket engine provide? (b)What is the initial acceleration of the rocket? (c)What is the final velocity Vf when the rocket mass become 180 kg(Vo=0)? (2%,3%,3%) 4. Find the moment inertia of a hollow sphere (mass M) with inner and outer radius R1 ,and R2 ,respectively.(8%) 5. Consider the air friction is proportional to object's velocity. Now we throw ball 1 (mass m) up with initial velocity Vo, and simultaneous we drop ball 2 with mass m on the top of the ball 1, falling from rest at the height h. Find the time and height when two balls meet.(10%) 6. (a)Describe the principle and operation of laser.(6%) (b)Briefly explain the occurrence of low-temperature superconductor.(4%) 7. Two balls with equal mass are heading to the right and approaching each other with velocity 4 m/s and 2 m/s, respectively. If the collision is inelastic and the collision coefficient is 0.5. What are the final velocities of these two balls?(8%) 8. Fig. 1 gives, as a function of time t, the force component Fx that acts on a 3.00 kg ice block that move only along the x axis. At t=0, the block is moving in the positive direction of the axis, with a speed of 3.0 m/s. What are its (a) speed and (b) direction of travel at t=11 s?(4%, 4%) Fig. 1 http://www.wretch.cc/album/show.php?i=bugsblog&b=42&f=1522510944&p=0 9. In Fig. 2, a slab of mass m1=40 kg rests on a frictionless floor, and a block of mass m2=12 kg rests on top of the slab. Between block and slab, the coefficient of static friction is 0.60, and the coefficient of kinetic friction is 0.40. A horizontal force F of magnitude 120 N begins to pull directly on the block, as shown. In unit-vector notation, what are the resulting accelerations (a) the block and (b) the slab?(4%, 4%) Fig. 2 http://www.wretch.cc/album/show.php?i=bugsblog&b=42&f=1522510945&p=1 10. A boy is initially seated on the top of a hemispherical ice mound of radius R=12.8 m. He begins to slide down the ice, with a negligible initial speed (Fig. 3). Approximate the ice as being frictionless. At what height does the boy lose contact with the ice?(8%) Fig. 3 http://www.wretch.cc/album/show.php?i=bugsblog&b=42&f=1522510946&p=2 11. The potential energy of a diatomic molecule is given by U=(A/r^12)-(B/r^6), where r is the separation of the two atoms of the molecule and A and B are positive constants. This potential energy is associated with the force that binds the two atoms together. (a) Find the equilibrium separation--that is, the distance between the atoms at which the force on each atom is zero. Is the force repulsive(the atoms are pushed apart) or attractive(they are pulled together) if their separations is (b) smaller and (c) larger than the equilibrium separation?(2%, 3%, 3%) 12. In Fig. 4, a block slides along a path that is without friction until the block reaches the section of L=0.65 m, which begins at height h=2.0 m on a ramp of angle θ=30度. In that section, the coefficient of kinetic friction is 0.40. The block passes through point A with a speed of 8.0 m/s. If the block can reach point B(where the friction ends), what is its speed there, and if it cannot, what is its greatest height above A?(4%, 4%) Fig. 4 http://www.wretch.cc/album/show.php?i=bugsblog&b=42&f=1522510947&p=3 --

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